The invention relates to an X-ray diagnostic unit for producing layer images of a radiography subject with a patient support, with a rotatable scanning system for irradiating the radiography subject from various directions comprising an X-ray tube which emits a beam of X-rays which penetrates the layer to be examined and whose dimension perpendicular to the layer plane is equal to the layer thickness, and a radiation receiver which supplies electrical output signals corresponding to the measured radiation intensity, with an X-ray generator for supplying the X-ray tube and with a computer connected to the radiation receiver for calculating the attenuation values of specific image points of the irradiated body layer from the output signals of the radiation receiver.
With a computer-tomograph of this type, the time of examination is determined essentially by the scanning time of the scanning system. The known method is to rotate the scanning system by an angle of approximately 360.degree. about the patient for one scan and then move it back again into its starting position for the next scan. In this case, the X-ray tube may be connected via high voltage cable to the X-ray generator and the detector may be connected via cable to the electronic device processing the measured values. The times required for accelerating the scanning system, however, determine lower limits for the scanning time. It would be possible to shorten the scanning time if the scanning system could be moved more quickly, more particularly if it were continuously rotating. In this case cables for supplying current or conducting away signals could no longer be used for the X-ray tube or for the radiation receiver.